ref: 42dfac6916ebbdac65cbec8b3e1a80c3ee41423c
dir: /appl/lib/w3c/css.b/
implement CSS;
#
# CSS2 parsing module
#
# CSS2.1 style sheets
#
# Copyright © 2001, 2005 Vita Nuova Holdings Limited. All rights reserved.
#
include "sys.m";
sys: Sys;
include "css.m";
B, NUMBER, IDENT, STRING, URL, PERCENTAGE, UNIT,
HASH, ATKEYWORD, IMPORTANT, IMPORT, PSEUDO, CLASS, INCLUDES,
DASHMATCH, FUNCTION: con 16rE000+iota;
toknames := array[] of{
B-B => "Zero",
NUMBER-B => "NUMBER",
IDENT-B => "IDENT",
STRING-B => "STRING",
URL-B => "URL",
PERCENTAGE-B => "PERCENTAGE",
UNIT-B => "UNIT",
HASH-B => "HASH",
ATKEYWORD-B => "ATKEYWORD",
IMPORTANT-B => "IMPORTANT",
CLASS-B => "CLASS",
INCLUDES-B => "INCLUDES",
DASHMATCH-B => "DASHMATCH",
PSEUDO-B => "PSEUDO",
FUNCTION-B => "FUNCTION",
};
printdiag := 0;
init(d: int)
{
sys = load Sys Sys->PATH;
printdiag = d;
}
parse(s: string): (ref Stylesheet, string)
{
return stylesheet(ref Cparse(-1, 0, nil, nil, Clex.new(s,1)));
}
parsedecl(s: string): (list of ref Decl, string)
{
return (declarations(ref Cparse(-1, 0, nil, nil, Clex.new(s,0))), nil);
}
ptok(c: int): string
{
if(c < 0)
return "eof";
if(c == 0)
return "zero?";
if(c >= B)
return sys->sprint("%s", toknames[c-B]);
return sys->sprint("%c", c);
}
Cparse: adt {
lookahead: int;
eof: int;
value: string;
suffix: string;
cs: ref Clex;
get: fn(nil: self ref Cparse): int;
look: fn(nil: self ref Cparse): int;
unget: fn(nil: self ref Cparse, tok: int);
skipto: fn(nil: self ref Cparse, followset: string): int;
synerr: fn(nil: self ref Cparse, s: string);
};
Cparse.get(p: self ref Cparse): int
{
if((c := p.lookahead) >= 0){
p.lookahead = -1;
return c;
}
if(p.eof)
return -1;
(c, p.value, p.suffix) = csslex(p.cs);
if(c < 0)
p.eof = 1;
if(printdiag > 1)
sys->print("lex: %s v=%s s=%s\n", ptok(c), p.value, p.suffix);
return c;
}
Cparse.look(p: self ref Cparse): int
{
c := p.get();
p.unget(c);
return c;
}
Cparse.unget(p: self ref Cparse, c: int)
{
if(p.lookahead >= 0)
raise "css: internal error: Cparse.unget";
p.lookahead = c; # note that p.value and p.suffix are assumed to be those of c
}
Cparse.skipto(p: self ref Cparse, followset: string): int
{
while((c := p.get()) >= 0)
for(i := 0; i < len followset; i++)
if(followset[i] == c){
p.unget(c);
return c;
}
return -1;
}
Cparse.synerr(p: self ref Cparse, s: string)
{
p.cs.synerr(s);
}
#
# stylesheet:
# ["@charset" STRING ';']?
# [CDO|CDC]* [import [CDO|CDC]*]*
# [[ruleset | media | page ] [CDO|CDC]*]*
# import:
# "@import" [STRING|URL] [ medium [',' medium]*]? ';'
# media:
# "@media" medium [',' medium]* '{' ruleset* '}'
# medium:
# IDENT
# page:
# "@page" pseudo_page? '{' declaration [';' declaration]* '}'
# pseudo_page:
# ':' IDENT
#
stylesheet(p: ref Cparse): (ref Stylesheet, string)
{
charset: string;
if(atkeywd(p, "@charset")){
if(itisa(p, STRING)){
charset = p.value;
itisa(p, ';');
}else
p.synerr("bad @charset declaration");
}
imports: list of ref Import;
while(atkeywd(p, "@import")){
c := p.get();
if(c == STRING || c == URL){
name := p.value;
media: list of string;
c = p.get();
if(c == IDENT){ # optional medium [, ...]
p.unget(c);
media = medialist(p);
}
imports = ref Import(name, media) :: imports;
}else
p.synerr("bad @import");
if(c != ';'){
p.synerr("missing ; in @import");
p.unget(c);
if(p.skipto(";}") < 0)
break;
}
}
imports = rev(imports);
stmts: list of ref Statement;
do{
while((c := p.get()) == ATKEYWORD)
case p.value {
"@media" => # medium[,medium]* { ruleset*}
media := medialist(p);
if(!itisa(p, '{')){
p.synerr("bad @media");
skipatrule("@media", p);
continue;
}
rules: list of ref Statement.Ruleset;
do{
rule := checkrule(p);
if(rule != nil)
rules = rule :: rules;
}while(!itisa(p, '}') && !p.eof);
stmts = ref Statement.Media(media, rev(rules)) :: stmts;
"@page" => # [:ident]? { declaration [; declaration]* }
pseudo: string;
if(itisa(p, PSEUDO))
pseudo = p.value;
if(!itisa(p, '{')){
p.synerr("bad @page");
skipatrule("@page", p);
continue;
}
decls := declarations(p);
if(!itisa(p, '}')){
p.synerr("unclosed @page declaration block");
skipatrule("@page", p);
continue;
}
stmts = ref Statement.Page(pseudo, decls) :: stmts;
* =>
skipatrule(p.value, p); # skip unknown or misplaced at-rule
}
p.unget(c);
rule := checkrule(p);
if(rule != nil)
stmts = rule :: stmts;
}while(!p.eof);
rl := stmts;
stmts = nil;
for(; rl != nil; rl = tl rl)
stmts = hd rl :: stmts;
return (ref Stylesheet(charset, imports, stmts), nil);
}
checkrule(p: ref Cparse): ref Statement.Ruleset
{
(rule, err) := ruleset(p);
if(rule == nil){
if(err != nil){
p.synerr(sys->sprint("bad ruleset: %s", err));
p.get(); # make some progress
}
}
return rule;
}
medialist(p: ref Cparse): list of string
{
media: list of string;
do{
c := p.get();
if(c != IDENT){
p.unget(c);
p.synerr("missing medium identifier");
break;
}
media = p.value :: media;
}while(itisa(p, ','));
return rev(media);
}
itisa(p: ref Cparse, expect: int): int
{
if((c := p.get()) == expect)
return 1;
p.unget(c);
return 0;
}
atkeywd(p: ref Cparse, expect: string): int
{
if((c := p.get()) == ATKEYWORD && p.value == expect)
return 1;
p.unget(c);
return 0;
}
skipatrule(name: string, p: ref Cparse)
{
if(printdiag)
sys->print("skip unimplemented or misplaced %s\n", name);
if((c := p.get()) == '{'){ # block
for(nesting := '}' :: nil; nesting != nil && c >= 0; nesting = tl nesting){
while((c = p.cs.getc()) >= 0 && c != hd nesting)
case c {
'{' =>
nesting = '}' :: nesting;
'(' =>
nesting = ')' :: nesting;
'[' =>
nesting = ']' :: nesting;
'"' or '\'' =>
quotedstring(p.cs, c);
}
}
}else{
while(c >= 0 && c != ';')
c = p.get();
}
}
# ruleset:
# selector [',' S* selector]* '{' S* declaration [';' S* declaration]* '}' S*
ruleset(p: ref Cparse): (ref Statement.Ruleset, string)
{
selectors: list of list of (int, list of ref Select);
c := -1;
do{
s := selector(p);
if(s == nil){
if(p.eof)
return (nil, nil);
p.synerr("expected selector");
if(p.skipto(",{}") < 0)
return (nil, nil);
c = p.look();
}else
selectors = s :: selectors;
}while((c = p.get()) == ',');
if(c != '{')
return (nil, "expected declaration block");
sl := selectors;
selectors = nil;
for(; sl != nil; sl = tl sl)
selectors = hd sl :: selectors;
decls := declarations(p);
if(!itisa(p, '}')){
p.synerr("unclosed declaration block");
}
return (ref Statement.Ruleset(selectors, decls), nil);
}
declarations(p: ref Cparse): list of ref Decl
{
decls: list of ref Decl;
c: int;
do{
(d, e) := declaration(p);
if(d != nil)
decls = d :: decls;
else if(e != nil){
p.synerr("ruleset declaration: "+e);
if((c = p.skipto(";}")) < 0)
break;
}
}while((c = p.get()) == ';');
p.unget(c);
l := decls;
for(decls = nil; l != nil; l = tl l)
decls = hd l :: decls;
return decls;
}
# selector:
# simple_selector [combinator simple_selector]*
# combinator:
# '+' S* | '>' S* | /* empty */
#
selector(p: ref Cparse): list of (int, list of ref Select)
{
sel: list of (int, list of ref Select);
op := ' ';
while((s := selector1(p)) != nil){
sel = (op, s) :: sel;
if((c := p.look()) == '+' || c == '>')
op = p.get();
else
op = ' ';
}
l: list of (int, list of ref Select);
for(; sel != nil; sel = tl sel)
l = hd sel :: l;
return l;
}
#
# simple_selector:
# element_name? [HASH | class | attrib | pseudo]* S*
# element_name:
# IDENT | '*'
# class:
# '.' IDENT
# attrib:
# '[' S* IDENT S* [ [ '=' | INCLUDES | DASHMATCH ] S* [IDENT | STRING] S* ]? ']'
# pseudo
# ':' [ IDENT | FUNCTION S* IDENT? S* ')' ]
selector1(p: ref Cparse): list of ref Select
{
sel: list of ref Select;
c := p.get();
if(c == IDENT)
sel = ref Select.Element(p.value) :: sel;
else if(c== '*')
sel = ref Select.Any("*") :: sel;
else
p.unget(c);
Sel:
for(;;){
c = p.get();
case c {
HASH =>
sel = ref Select.ID(p.value) :: sel;
CLASS =>
sel = ref Select.Class(p.value) :: sel;
'[' =>
if(!itisa(p, IDENT))
break;
name := p.value;
case c = p.get() {
'=' =>
sel = ref Select.Attrib(name, "=", optaval(p)) :: sel;
INCLUDES =>
sel = ref Select.Attrib(name, "~=", optaval(p)) :: sel;
DASHMATCH =>
sel = ref Select.Attrib(name, "|=", optaval(p)) :: sel;
* =>
sel = ref Select.Attrib(name, nil, nil) :: sel;
p.unget(c);
}
if((c = p.get()) != ']'){
p.synerr("bad attribute syntax");
p.unget(c);
break Sel;
}
PSEUDO =>
case c = p.get() {
IDENT =>
sel = ref Select.Pseudo(p.value) :: sel;
FUNCTION =>
name := p.value;
case c = p.get() {
IDENT =>
sel = ref Select.Pseudofn(name, lowercase(p.value)) :: sel;
')' =>
p.unget(c);
sel = ref Select.Pseudofn(name, nil) :: sel;
* =>
p.synerr("bad pseudo-function syntax");
p.unget(c);
break Sel;
}
if((c = p.get()) != ')'){
p.synerr("missing ')' for pseudo-function");
p.unget(c);
break Sel;
}
* =>
p.synerr(sys->sprint("unexpected :pseudo: %s:%s", ptok(c), p.value));
p.unget(c);
break Sel;
}
* =>
p.unget(c);
break Sel;
}
# qualifiers must be adjacent to the first item, and each other
c = p.cs.getc();
p.cs.ungetc(c);
if(isspace(c))
break;
}
sl := sel;
for(sel = nil; sl != nil; sl = tl sl)
sel = hd sl :: sel;
return sel;
}
optaval(p: ref Cparse): ref Value
{
case c := p.get() {
IDENT =>
return ref Value.Ident(' ', p.value);
STRING =>
return ref Value.String(' ', p.value);
* =>
p.unget(c);
return nil;
}
}
# declaration:
# property ':' S* expr prio?
# | /* empty */
# property:
# IDENT
# prio:
# IMPORTANT S* /* ! important */
declaration(p: ref Cparse): (ref Decl, string)
{
c := p.get();
if(c != IDENT){
p.unget(c);
return (nil, nil);
}
prop := lowercase(p.value);
c = p.get();
if(c != ':'){
p.unget(c);
return (nil, "missing :");
}
values := expr(p);
if(values == nil)
return (nil, "missing expression(s)");
prio := 0;
if(p.look() == IMPORTANT){
p.get();
prio = 1;
}
return (ref Decl(prop, values, prio), nil);
}
# expr:
# term [operator term]*
# operator:
# '/' | ',' | /* empty */
expr(p: ref Cparse): list of ref Value
{
values: list of ref Value;
sep := ' ';
while((t := term(p, sep)) != nil){
values = t :: values;
if((c := p.look()) == '/' || c == ',')
sep = p.get(); # need something fancier here?
else
sep = ' ';
}
vl := values;
for(values = nil; vl != nil; vl = tl vl)
values = hd vl :: values;
return values;
}
#
# term:
# unary_operator? [NUMBER | PERCENTAGE | LENGTH | EMS | EXS | ANGLE | TIME | FREQ | function]
# | STRING | IDENT | URI | RGB | UNICODERANGE | hexcolour
# function:
# FUNCTION expr ')'
# unary_operator:
# '-' | '+'
# hexcolour:
# HASH S*
#
# LENGTH, EMS, ... FREQ have been combined into UNIT here
#
# TO DO: UNICODERANGE
term(p: ref Cparse, sep: int): ref Value
{
prefix: string;
case p.look(){
'+' or '-' =>
prefix[0] = p.get();
}
c := p.get();
case c {
NUMBER =>
return ref Value.Number(sep, prefix+p.value);
PERCENTAGE =>
return ref Value.Percentage(sep, prefix+p.value);
UNIT =>
return ref Value.Unit(sep, prefix+p.value, p.suffix);
}
if(prefix != nil)
p.synerr("+/- before non-numeric");
case c {
STRING =>
return ref Value.String(sep, p.value);
IDENT =>
return ref Value.Ident(sep, lowercase(p.value));
URL =>
return ref Value.Url(sep, p.value);
HASH =>
# could check value: 3 or 6 hex digits
(r, g, b) := torgb(p.value);
if(r < 0)
return nil;
return ref Value.Hexcolour(sep, p.value, (r,g,b));
FUNCTION =>
name := p.value;
args := expr(p);
c = p.get();
if(c != ')'){
p.synerr(sys->sprint("missing ')' for function %s", name));
return nil;
}
if(name == "rgb"){
if(len args != 3){
p.synerr("wrong number of arguments to rgb()");
return nil;
}
r := colourof(hd args);
g := colourof(hd tl args);
b := colourof(hd tl tl args);
if(r < 0 || g < 0 || b < 0){
p.synerr("invalid rgb() parameters");
return nil;
}
return ref Value.RGB(sep, args, (r,g,b));
}
return ref Value.Function(sep, name, args);
* =>
p.unget(c);
return nil;
}
}
torgb(s: string): (int, int, int)
{
case len s {
3 =>
r := hex(s[0]);
g := hex(s[1]);
b := hex(s[2]);
if(r >= 0 && g >= 0 && b >= 0)
return ((r<<4)|r, (g<<4)|g, (b<<4)|b);
6 =>
v := 0;
for(i := 0; i < 6; i++){
n := hex(s[i]);
if(n < 0)
return (-1, 0, 0);
v = (v<<4) | n;
}
return (v>>16, (v>>8)&16rFF, v&16rFF);
}
return (-1, 0, 0);
}
colourof(v: ref Value): int
{
pick r := v {
Number =>
return clip(int r.value, 0, 255);
Percentage =>
# just the integer part
return clip((int r.value*255 + 50)/100, 0, 255);
* =>
return -1;
}
}
clip(v: int, l: int, u: int): int
{
if(v < l)
return l;
if(v > u)
return u;
return v;
}
rev[T](l: list of T): list of T
{
t: list of T;
for(; l != nil; l = tl l)
t = hd l :: t;
return t;
}
Clex: adt {
context: list of int; # characters
input: string;
lim: int;
n: int;
lineno: int;
new: fn(s: string, lno: int): ref Clex;
getc: fn(cs: self ref Clex): int;
ungetc: fn(cs: self ref Clex, c: int);
synerr: fn(nil: self ref Clex, s: string);
};
Clex.new(s: string, lno: int): ref Clex
{
return ref Clex(nil, s, len s, 0, lno);
}
Clex.getc(cs: self ref Clex): int
{
if(cs.context != nil){
c := hd cs.context;
cs.context = tl cs.context;
return c;
}
if(cs.n >= cs.lim)
return -1;
c := cs.input[cs.n++];
if(c == '\n')
cs.lineno++;
return c;
}
Clex.ungetc(cs: self ref Clex, c: int)
{
cs.context = c :: cs.context;
}
Clex.synerr(cs: self ref Clex, s: string)
{
if(printdiag)
sys->fprint(sys->fildes(2), "%d: err: %s\n", cs.lineno, s);
}
csslex(cs: ref Clex): (int, string, string)
{
for(;;){
c := skipws(cs);
if(c < 0)
return (-1, nil, nil);
case c {
'<' =>
if(seq(cs, "!--"))
break; # <!-- ignore HTML comment start (CDO)
return (c, nil, nil);
'-' =>
if(seq(cs, "->"))
break; # --> ignore HTML comment end (CDC)
return (c, nil, nil);
':' =>
c = cs.getc();
cs.ungetc(c);
if(isnamec(c, 0))
return (PSEUDO, nil, nil);
return (':', nil, nil);
'#' =>
c = cs.getc();
if(isnamec(c, 1))
return (HASH, name(cs, c), nil);
cs.ungetc(c);
return ('#', nil, nil);
'/' =>
if(subseq(cs, '*', 1, 0)){
comment(cs);
break;
}
return (c, nil, nil);
'\'' or '"' =>
return (STRING, quotedstring(cs, c), nil);
'0' to '9' or '.' =>
if(c == '.'){
d := cs.getc();
cs.ungetc(d);
if(!isdigit(d)){
if(isnamec(d, 1))
return (CLASS, name(cs, cs.getc()), nil);
return ('.', nil, nil);
}
# apply CSS2 treatment: .55 is a number not a class
}
val := number(cs, c);
c = cs.getc();
if(c == '%')
return (PERCENTAGE, val, "%");
if(isnamec(c, 0)) # use CSS2 interpetation
return (UNIT, val, lowercase(name(cs, c)));
cs.ungetc(c);
return (NUMBER, val, nil);
'\\' =>
d := cs.getc();
if(d >= ' ' && d <= '~' || islatin1(d)){ # probably should handle it in name
wd := name(cs, d);
return (IDENT, "\\"+wd, nil);
}
cs.ungetc(d);
return ('\\', nil, nil);
'@' =>
c = cs.getc();
if(isnamec(c, 0)) # @something
return (ATKEYWORD, "@"+lowercase(name(cs,c)), nil);
cs.ungetc(c);
return ('@', nil, nil);
'!' =>
c = skipws(cs);
if(isnamec(c, 0)){ # !something
wd := name(cs, c);
if(lowercase(wd) == "important")
return (IMPORTANT, nil, nil);
pushback(cs, wd);
}else
cs.ungetc(c);
return ('!', nil, nil);
'~' =>
if(subseq(cs, '=', 1, 0))
return (INCLUDES, "~=", nil);
return ('~', nil, nil);
'|' =>
if(subseq(cs, '=', 1, 0))
return (DASHMATCH, "|=", nil);
return ('|', nil, nil);
* =>
if(isnamec(c, 0)){
wd := name(cs, c);
d := cs.getc();
if(d != '('){
cs.ungetc(d);
return (IDENT, wd, nil);
}
val := lowercase(wd);
if(val == "url")
return (URL, url(cs), nil); # bizarre special case
return (FUNCTION, val, nil);
}
return (c, nil, nil);
}
}
}
skipws(cs: ref Clex): int
{
for(;;){
while((c := cs.getc()) == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f')
;
if(c != '/')
return c;
c = cs.getc();
if(c != '*'){
cs.ungetc(c);
return '/';
}
comment(cs);
}
}
seq(cs: ref Clex, s: string): int
{
for(i := 0; i < len s; i++)
if((c := cs.getc()) != s[i])
break;
if(i == len s)
return 1;
cs.ungetc(c);
while(i > 0)
cs.ungetc(s[--i]);
if(c < 0)
return -1;
return 0;
}
subseq(cs: ref Clex, a: int, t: int, e: int): int
{
if((c := cs.getc()) != a){
cs.ungetc(c);
return e;
}
return t;
}
pushback(cs: ref Clex, wd: string)
{
for(i := len wd; --i >= 0;)
cs.ungetc(wd[i]);
}
comment(cs: ref Clex)
{
while((c := cs.getc()) != '*' || (c = cs.getc()) != '/')
if(c < 0) {
# end of file in comment
break;
}
}
number(cs: ref Clex, c: int): string
{
s: string;
for(; isdigit(c); c = cs.getc())
s[len s] = c;
if(c != '.'){
cs.ungetc(c);
return s;
}
if(!isdigit(c = cs.getc())){
cs.ungetc(c);
cs.ungetc('.');
return s;
}
s[len s] = '.';
do{
s[len s] = c;
}while(isdigit(c = cs.getc()));
cs.ungetc(c);
return s;
}
name(cs: ref Clex, c: int): string
{
s: string;
for(; isnamec(c, 1); c = cs.getc()){
s[len s] = c;
if(c == '\\'){
c = cs.getc();
if(isescapable(c))
s[len s] = c;
}
}
cs.ungetc(c);
return s;
}
isescapable(c: int): int
{
return c >= ' ' && c <= '~' || isnamec(c, 1);
}
islatin1(c: int): int
{
return c >= 16rA1 && c <= 16rFF; # printable latin-1
}
isnamec(c: int, notfirst: int): int
{
return c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z' || c == '\\' ||
notfirst && (c >= '0' && c <= '9' || c == '-') ||
c >= 16rA1 && c <= 16rFF; # printable latin-1
}
isxdigit(c: int): int
{
return c>='0' && c<='9' || c>='a'&&c<='f' || c>='A'&&c<='F';
}
isdigit(c: int): int
{
return c >= '0' && c <= '9';
}
isspace(c: int): int
{
return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f';
}
hex(c: int): int
{
if(c >= '0' && c <= '9')
return c-'0';
if(c >= 'A' && c <= 'F')
return c-'A' + 10;
if(c >= 'a' && c <= 'f')
return c-'a' + 10;
return -1;
}
quotedstring(cs: ref Clex, delim: int): string
{
s: string;
while((c := cs.getc()) != delim){
if(c < 0){
cs.synerr("end-of-file in string");
return s;
}
if(c == '\\'){
c = cs.getc();
if(c < 0){
cs.synerr("end-of-file in string");
return s;
}
if(isxdigit(c)){
# unicode escape
n := 0;
for(i := 0;;){
n = (n<<4) | hex(c);
c = cs.getc();
if(!isxdigit(c) || ++i >= 6){
if(!isspace(c))
cs.ungetc(c); # CSS2 ignores the first white space following
break;
}
}
s[len s] = n;
}else if(c == '\n'){
; # escaped newline
}else if(isescapable(c))
s[len s] = c;
}else if(c)
s[len s] = c;
}
return s;
}
url(cs: ref Clex): string
{
s: string;
c := skipws(cs);
if(c != '"' && c != '\''){ # not a quoted string
while(c != ' ' && c != '\n' && c != '\'' && c != '"' && c != ')'){
s[len s] = c;
c = cs.getc();
if(c == '\\'){
c = cs.getc();
if(c < 0){
cs.synerr("end of file in url parameter");
break;
}
if(c == ' ' || c == '\'' || c == '"' || c == ')')
s[len s] = c;
else{
cs.synerr("invalid escape sequence in url");
s[len s] = '\\';
s[len s] = c;
}
c = cs.getc();
}
}
cs.ungetc(c);
# if(s == nil)
# p.synerr("empty parameter to url");
}else
s = quotedstring(cs, c);
if((c = skipws(cs)) != ')'){
cs.synerr("unclosed parameter to url");
cs.ungetc(c);
}
return s;
}
lowercase(s: string): string
{
for(i := 0; i < len s; i++)
if((c := s[i]) >= 'A' && c <= 'Z')
s[i] = c-'A' + 'a';
return s;
}